diff --git a/ipv4/defs_netbsd.go b/ipv4/defs_netbsd.go
index cfde2363..21fe7f4c 100644
--- a/ipv4/defs_netbsd.go
+++ b/ipv4/defs_netbsd.go
@@ -15,23 +15,10 @@ package ipv4
 import "C"
 
 const (
-	sysIP_OPTIONS     = C.IP_OPTIONS
-	sysIP_HDRINCL     = C.IP_HDRINCL
-	sysIP_TOS         = C.IP_TOS
-	sysIP_TTL         = C.IP_TTL
-	sysIP_RECVOPTS    = C.IP_RECVOPTS
-	sysIP_RECVRETOPTS = C.IP_RECVRETOPTS
 	sysIP_RECVDSTADDR = C.IP_RECVDSTADDR
-	sysIP_RETOPTS     = C.IP_RETOPTS
 	sysIP_RECVIF      = C.IP_RECVIF
 	sysIP_RECVTTL     = C.IP_RECVTTL
 
-	sysIP_MULTICAST_IF    = C.IP_MULTICAST_IF
-	sysIP_MULTICAST_TTL   = C.IP_MULTICAST_TTL
-	sysIP_MULTICAST_LOOP  = C.IP_MULTICAST_LOOP
-	sysIP_ADD_MEMBERSHIP  = C.IP_ADD_MEMBERSHIP
-	sysIP_DROP_MEMBERSHIP = C.IP_DROP_MEMBERSHIP
-
 	sizeofIPMreq = C.sizeof_struct_ip_mreq
 )
 
diff --git a/ipv4/defs_openbsd.go b/ipv4/defs_openbsd.go
index cfde2363..21fe7f4c 100644
--- a/ipv4/defs_openbsd.go
+++ b/ipv4/defs_openbsd.go
@@ -15,23 +15,10 @@ package ipv4
 import "C"
 
 const (
-	sysIP_OPTIONS     = C.IP_OPTIONS
-	sysIP_HDRINCL     = C.IP_HDRINCL
-	sysIP_TOS         = C.IP_TOS
-	sysIP_TTL         = C.IP_TTL
-	sysIP_RECVOPTS    = C.IP_RECVOPTS
-	sysIP_RECVRETOPTS = C.IP_RECVRETOPTS
 	sysIP_RECVDSTADDR = C.IP_RECVDSTADDR
-	sysIP_RETOPTS     = C.IP_RETOPTS
 	sysIP_RECVIF      = C.IP_RECVIF
 	sysIP_RECVTTL     = C.IP_RECVTTL
 
-	sysIP_MULTICAST_IF    = C.IP_MULTICAST_IF
-	sysIP_MULTICAST_TTL   = C.IP_MULTICAST_TTL
-	sysIP_MULTICAST_LOOP  = C.IP_MULTICAST_LOOP
-	sysIP_ADD_MEMBERSHIP  = C.IP_ADD_MEMBERSHIP
-	sysIP_DROP_MEMBERSHIP = C.IP_DROP_MEMBERSHIP
-
 	sizeofIPMreq = C.sizeof_struct_ip_mreq
 )
 
diff --git a/ipv4/sys_bsd.go b/ipv4/sys_bsd.go
index 8074f989..e8299b41 100644
--- a/ipv4/sys_bsd.go
+++ b/ipv4/sys_bsd.go
@@ -13,26 +13,28 @@ import (
 
 	"golang.org/x/net/internal/iana"
 	"golang.org/x/net/internal/socket"
+
+	"golang.org/x/sys/unix"
 )
 
 var (
 	ctlOpts = [ctlMax]ctlOpt{
-		ctlTTL:       {sysIP_RECVTTL, 1, marshalTTL, parseTTL},
-		ctlDst:       {sysIP_RECVDSTADDR, net.IPv4len, marshalDst, parseDst},
-		ctlInterface: {sysIP_RECVIF, syscall.SizeofSockaddrDatalink, marshalInterface, parseInterface},
+		ctlTTL:       {unix.IP_RECVTTL, 1, marshalTTL, parseTTL},
+		ctlDst:       {unix.IP_RECVDSTADDR, net.IPv4len, marshalDst, parseDst},
+		ctlInterface: {unix.IP_RECVIF, syscall.SizeofSockaddrDatalink, marshalInterface, parseInterface},
 	}
 
 	sockOpts = map[int]*sockOpt{
-		ssoTOS:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TOS, Len: 4}},
-		ssoTTL:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TTL, Len: 4}},
-		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_TTL, Len: 1}},
-		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_IF, Len: 4}},
-		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_LOOP, Len: 1}},
-		ssoReceiveTTL:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVTTL, Len: 4}},
-		ssoReceiveDst:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVDSTADDR, Len: 4}},
-		ssoReceiveInterface:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVIF, Len: 4}},
-		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_HDRINCL, Len: 4}},
-		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_ADD_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
-		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_DROP_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
+		ssoTOS:                {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_TOS, Len: 4}},
+		ssoTTL:                {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_TTL, Len: 4}},
+		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_TTL, Len: 1}},
+		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_IF, Len: 4}},
+		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_LOOP, Len: 1}},
+		ssoReceiveTTL:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVTTL, Len: 4}},
+		ssoReceiveDst:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVDSTADDR, Len: 4}},
+		ssoReceiveInterface:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVIF, Len: 4}},
+		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_HDRINCL, Len: 4}},
+		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_ADD_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
+		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_DROP_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
 	}
 )
diff --git a/ipv4/zsys_netbsd.go b/ipv4/zsys_netbsd.go
index 8cfc648a..df99ef69 100644
--- a/ipv4/zsys_netbsd.go
+++ b/ipv4/zsys_netbsd.go
@@ -4,23 +4,10 @@
 package ipv4
 
 const (
-	sysIP_OPTIONS     = 0x1
-	sysIP_HDRINCL     = 0x2
-	sysIP_TOS         = 0x3
-	sysIP_TTL         = 0x4
-	sysIP_RECVOPTS    = 0x5
-	sysIP_RECVRETOPTS = 0x6
 	sysIP_RECVDSTADDR = 0x7
-	sysIP_RETOPTS     = 0x8
 	sysIP_RECVIF      = 0x14
 	sysIP_RECVTTL     = 0x17
 
-	sysIP_MULTICAST_IF    = 0x9
-	sysIP_MULTICAST_TTL   = 0xa
-	sysIP_MULTICAST_LOOP  = 0xb
-	sysIP_ADD_MEMBERSHIP  = 0xc
-	sysIP_DROP_MEMBERSHIP = 0xd
-
 	sizeofIPMreq = 0x8
 )
 
diff --git a/ipv4/zsys_openbsd.go b/ipv4/zsys_openbsd.go
index 37629cb0..9052a9bd 100644
--- a/ipv4/zsys_openbsd.go
+++ b/ipv4/zsys_openbsd.go
@@ -4,23 +4,10 @@
 package ipv4
 
 const (
-	sysIP_OPTIONS     = 0x1
-	sysIP_HDRINCL     = 0x2
-	sysIP_TOS         = 0x3
-	sysIP_TTL         = 0x4
-	sysIP_RECVOPTS    = 0x5
-	sysIP_RECVRETOPTS = 0x6
 	sysIP_RECVDSTADDR = 0x7
-	sysIP_RETOPTS     = 0x8
 	sysIP_RECVIF      = 0x1e
 	sysIP_RECVTTL     = 0x1f
 
-	sysIP_MULTICAST_IF    = 0x9
-	sysIP_MULTICAST_TTL   = 0xa
-	sysIP_MULTICAST_LOOP  = 0xb
-	sysIP_ADD_MEMBERSHIP  = 0xc
-	sysIP_DROP_MEMBERSHIP = 0xd
-
 	sizeofIPMreq = 0x8
 )